Subfloor preparation

[copea]

I'm about to take on the tiling of the floor in my bathroom and I'd like to check I'm heading the right way please?
Any pointers welcome.

The floor has been taken up and the joists are exposed at the moment, so my plan is to fit:

- 18mm WBP ply, fixed at 300 centres with 45mm Floortite screws.
- Layer of Mapei Keraflex Maxi S1 adhesive (4.5mm trowel).
- 6mm underfloor heating insulation boards fixed at 300 centres.
- Prime floor as per underfloor heating cable manufacturer's instructions.
- Underfloor heating cables.
- Layer of Mapei Ultraplan Renovation Screed.
- Layer of Mapei Keraflex Maxi S1 adhesive (4.5mm trowel).
- Lay 2" hexagon mosaic floor tiles.

I was initially planning not to install underfloor heating and to use Ditra matting.
Do the insulation boards act as the decoupling membrane in the situation I've described above, or do I need Ditra matting too?

 

[Paul C.]

Wow. Someone has been doing their homework

Everything you have said is spot on. Providing it is a cement coated insulation board you have (like Marmox or Wedi), then it will have decoupling properties as the foam can de-bond from the coating if there is significant movement.